11,075 research outputs found
Phantom inflation and the "Big Trip"
Primordial inflation is regarded to be driven by a phantom field which is
here implemented as a scalar field satisfying an equation of state
, with . Being even aggravated by the weird properties
of phantom energy, this will pose a serious problem with the exit from the
inflationary phase. We argue however in favor of the speculation that a smooth
exit from the phantom inflationary phase can still be tentatively recovered by
considering a multiverse scenario where the primordial phantom universe would
travel in time toward a future universe filled with usual radiation, before
reaching the big rip. We call this transition the "big trip" and assume it to
take place with the help of some form of anthropic principle which chooses our
current universe as being the final destination of the time transition.Comment: 23 pages, 5 figures, LaTex, Phys. Lett. B (in press
A comprehensive study of rate capability in Multi-Wire Proportional Chambers
Systematic measurements on the rate capability of thin MWPCs operated in
Xenon, Argon and Neon mixtures using CO2 as UV-quencher are presented. A good
agreement between data and existing models has been found, allowing us to
present the rate capability of MWPCs in a comprehensive way and ultimately
connect it with the mobilities of the drifting ions.Comment: 29 pages, 18 figure
Cup products on polyhedral approximations of 3D digital images
Let I be a 3D digital image, and let Q(I) be the associated cubical complex. In this paper we show how to simplify the combinatorial structure of Q(I) and obtain a homeomorphic cellular complex P(I) with fewer cells. We introduce formulas for a diagonal approximation on a general polygon and use it to compute cup products on the cohomology H *(P(I)). The cup product encodes important geometrical information not captured by the cohomology groups. Consequently, the ring structure of H *(P(I)) is a finer topological invariant. The algorithm proposed here can be applied to compute cup products on any polyhedral approximation of an object embedded in 3-space
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